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Blood-derived inflammatory dendritic cells in lymph nodes stimulate acute T helper type 1 immune responses.

Nakano H, Lin KL, Yanagita M, Charbonneau C, Cook DN, Kakiuchi T, Gunn MD - Nat. Immunol. (2009)

Bottom Line: Here we found after viral infection or immunization, inflammatory monocytes were recruited into lymph nodes directly from the blood to become CD11c(+)CD11b(hi)Gr-1(+) inflammatory DCs, which produced abundant interleukin 12p70 and potently stimulated T(H)1 responses.This monocyte extravasation required the chemokine receptor CCR2 but not the chemokine CCL2 or receptor CCR7.We conclude that blood-derived inflammatory DCs are important in the development of T(H)1 immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.

ABSTRACT
T helper type 1 (T(H)1)-polarized immune responses, which confer protection against intracellular pathogens, are thought to be initiated by dendritic cells (DCs) that enter lymph nodes from peripheral tissues. Here we found after viral infection or immunization, inflammatory monocytes were recruited into lymph nodes directly from the blood to become CD11c(+)CD11b(hi)Gr-1(+) inflammatory DCs, which produced abundant interleukin 12p70 and potently stimulated T(H)1 responses. This monocyte extravasation required the chemokine receptor CCR2 but not the chemokine CCL2 or receptor CCR7. Thus, the accumulation of inflammatory DCs and T(H)1 responses were much lower in Ccr2(-/-) mice, were preserved in Ccl2(-/-) mice and were relatively higher in CCL19-CCL21-Ser-deficient plt mutant mice, in which all other lymph node DC types were fewer in number. We conclude that blood-derived inflammatory DCs are important in the development of T(H)1 immune responses.

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TH1 responses in the lymph nodes of Ccr2−/− and Ccl2−/− mice. (a–b) IFN-γ (a) and IL-2 (b) production by total lymph nodes cells isolated from WT, Ccr2−/− and Ccl2−/− mice 6 days after immunization with OVA/CFA. T cells were restimulated with OVA for 48 h and IFN-γ in the supernatant measured by ELISA. Data points represent mean ± SD, n = 3 mice. Significance determined by Student’s t-test. *p<0.05 (c,d) IFN-γ production by (c) and proliferation of (d) OT2 cells stimulated as in Fig. 4a with the indicated DC types. Data points represent mean ± SD for 3 experiments, each using cells pooled from 5–7 mice. Response curves were analyzed by linear regression, and P-value for slopes was determined by ANOVA. **p<0.0001 for WT Gr-1+ DC vs. all other DC types.
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Figure 6: TH1 responses in the lymph nodes of Ccr2−/− and Ccl2−/− mice. (a–b) IFN-γ (a) and IL-2 (b) production by total lymph nodes cells isolated from WT, Ccr2−/− and Ccl2−/− mice 6 days after immunization with OVA/CFA. T cells were restimulated with OVA for 48 h and IFN-γ in the supernatant measured by ELISA. Data points represent mean ± SD, n = 3 mice. Significance determined by Student’s t-test. *p<0.05 (c,d) IFN-γ production by (c) and proliferation of (d) OT2 cells stimulated as in Fig. 4a with the indicated DC types. Data points represent mean ± SD for 3 experiments, each using cells pooled from 5–7 mice. Response curves were analyzed by linear regression, and P-value for slopes was determined by ANOVA. **p<0.0001 for WT Gr-1+ DC vs. all other DC types.

Mentions: The finding that blood-derived inflammatory DCs accumulated in the lymph nodes of Ccl2−/− but not Ccr2−/− mice strongly suggests that these cells play an important role in stimulating TH1 immune responses. To directly compare TH1 T cell polarization in Ccr2−/− and Ccl2−/− mice, we examined lymph node T cells after subcutaneous immunization with OVA in CFA. Upon restimulation with OVA, IFN-γ production by T cells from Ccr2−/− mice was markedly reduced while T cells from Ccl2−/− mice displayed increased IFN-γ production (Fig. 6a). At the same time, T cells from Ccr2−/− and Ccl2−/− mice produced normal amounts of IL-2 (Fig. 6b). To confirm that the reduced T cell IFN-γ production seen in Ccr2−/− mice was due to a reduction in DC TH1-stimulatory activity, we examined this activity in wild-type and Ccr2−/− lymph node DC populations. To obtain sufficient cell numbers, DCs were purified from the mediastinal lymph nodes of influenza-infected mice. As above, CD11bhiGr-1+ DCs purified from wild-type lymph nodes stimulated robust T cell IFN-γ production (Fig. 6c). CD11bhiGr-1+ DCs were not present in the lymph nodes, spleens, or blood of infected Ccr2−/− mice and therefore could not be tested. CD11bhiGr-1− DCs purified from wild-type lymph nodes stimulated low amounts of IFN-γ, demonstrating a potency of about 25% that of Gr-1+ DCs. Among CD11bhiGr-1− DCs purified from Ccr2−/− lymph nodes, this activity was reduced, suggesting that a portion of inflammatory DCs may display a Gr-1− phenotype due to loss of Ly6-C expression30. CD8+ DCs from Ccr2−/− mice also stimulated production of low amounts of IFN-γ, with an activity similar to wild-type CD8+ DCs (compare Figs. 6c and 4a) but much lower than CD11bhi Gr-1+ DCs. These differences in TH1-stimulating activity are not due to differences in the stimulation of T cell proliferation (Fig. 6d). We conclude that the reduction in TH1 responses seen in Ccr2−/− mice was due to an absence of TH1-stimulatory inflammatory DC within inflamed lymph nodes.


Blood-derived inflammatory dendritic cells in lymph nodes stimulate acute T helper type 1 immune responses.

Nakano H, Lin KL, Yanagita M, Charbonneau C, Cook DN, Kakiuchi T, Gunn MD - Nat. Immunol. (2009)

TH1 responses in the lymph nodes of Ccr2−/− and Ccl2−/− mice. (a–b) IFN-γ (a) and IL-2 (b) production by total lymph nodes cells isolated from WT, Ccr2−/− and Ccl2−/− mice 6 days after immunization with OVA/CFA. T cells were restimulated with OVA for 48 h and IFN-γ in the supernatant measured by ELISA. Data points represent mean ± SD, n = 3 mice. Significance determined by Student’s t-test. *p<0.05 (c,d) IFN-γ production by (c) and proliferation of (d) OT2 cells stimulated as in Fig. 4a with the indicated DC types. Data points represent mean ± SD for 3 experiments, each using cells pooled from 5–7 mice. Response curves were analyzed by linear regression, and P-value for slopes was determined by ANOVA. **p<0.0001 for WT Gr-1+ DC vs. all other DC types.
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Figure 6: TH1 responses in the lymph nodes of Ccr2−/− and Ccl2−/− mice. (a–b) IFN-γ (a) and IL-2 (b) production by total lymph nodes cells isolated from WT, Ccr2−/− and Ccl2−/− mice 6 days after immunization with OVA/CFA. T cells were restimulated with OVA for 48 h and IFN-γ in the supernatant measured by ELISA. Data points represent mean ± SD, n = 3 mice. Significance determined by Student’s t-test. *p<0.05 (c,d) IFN-γ production by (c) and proliferation of (d) OT2 cells stimulated as in Fig. 4a with the indicated DC types. Data points represent mean ± SD for 3 experiments, each using cells pooled from 5–7 mice. Response curves were analyzed by linear regression, and P-value for slopes was determined by ANOVA. **p<0.0001 for WT Gr-1+ DC vs. all other DC types.
Mentions: The finding that blood-derived inflammatory DCs accumulated in the lymph nodes of Ccl2−/− but not Ccr2−/− mice strongly suggests that these cells play an important role in stimulating TH1 immune responses. To directly compare TH1 T cell polarization in Ccr2−/− and Ccl2−/− mice, we examined lymph node T cells after subcutaneous immunization with OVA in CFA. Upon restimulation with OVA, IFN-γ production by T cells from Ccr2−/− mice was markedly reduced while T cells from Ccl2−/− mice displayed increased IFN-γ production (Fig. 6a). At the same time, T cells from Ccr2−/− and Ccl2−/− mice produced normal amounts of IL-2 (Fig. 6b). To confirm that the reduced T cell IFN-γ production seen in Ccr2−/− mice was due to a reduction in DC TH1-stimulatory activity, we examined this activity in wild-type and Ccr2−/− lymph node DC populations. To obtain sufficient cell numbers, DCs were purified from the mediastinal lymph nodes of influenza-infected mice. As above, CD11bhiGr-1+ DCs purified from wild-type lymph nodes stimulated robust T cell IFN-γ production (Fig. 6c). CD11bhiGr-1+ DCs were not present in the lymph nodes, spleens, or blood of infected Ccr2−/− mice and therefore could not be tested. CD11bhiGr-1− DCs purified from wild-type lymph nodes stimulated low amounts of IFN-γ, demonstrating a potency of about 25% that of Gr-1+ DCs. Among CD11bhiGr-1− DCs purified from Ccr2−/− lymph nodes, this activity was reduced, suggesting that a portion of inflammatory DCs may display a Gr-1− phenotype due to loss of Ly6-C expression30. CD8+ DCs from Ccr2−/− mice also stimulated production of low amounts of IFN-γ, with an activity similar to wild-type CD8+ DCs (compare Figs. 6c and 4a) but much lower than CD11bhi Gr-1+ DCs. These differences in TH1-stimulating activity are not due to differences in the stimulation of T cell proliferation (Fig. 6d). We conclude that the reduction in TH1 responses seen in Ccr2−/− mice was due to an absence of TH1-stimulatory inflammatory DC within inflamed lymph nodes.

Bottom Line: Here we found after viral infection or immunization, inflammatory monocytes were recruited into lymph nodes directly from the blood to become CD11c(+)CD11b(hi)Gr-1(+) inflammatory DCs, which produced abundant interleukin 12p70 and potently stimulated T(H)1 responses.This monocyte extravasation required the chemokine receptor CCR2 but not the chemokine CCL2 or receptor CCR7.We conclude that blood-derived inflammatory DCs are important in the development of T(H)1 immune responses.

View Article: PubMed Central - PubMed

Affiliation: Department of Medicine, Duke University Medical Center, Durham, North Carolina, USA.

ABSTRACT
T helper type 1 (T(H)1)-polarized immune responses, which confer protection against intracellular pathogens, are thought to be initiated by dendritic cells (DCs) that enter lymph nodes from peripheral tissues. Here we found after viral infection or immunization, inflammatory monocytes were recruited into lymph nodes directly from the blood to become CD11c(+)CD11b(hi)Gr-1(+) inflammatory DCs, which produced abundant interleukin 12p70 and potently stimulated T(H)1 responses. This monocyte extravasation required the chemokine receptor CCR2 but not the chemokine CCL2 or receptor CCR7. Thus, the accumulation of inflammatory DCs and T(H)1 responses were much lower in Ccr2(-/-) mice, were preserved in Ccl2(-/-) mice and were relatively higher in CCL19-CCL21-Ser-deficient plt mutant mice, in which all other lymph node DC types were fewer in number. We conclude that blood-derived inflammatory DCs are important in the development of T(H)1 immune responses.

Show MeSH
Related in: MedlinePlus